Lock stitch sewing machine under bed mechanism



p 1953 R. K. HOHMANN ET AL LOCK STITCH SEWING MACHINE UNDER BED MECHANISM 2 Sheets-Sheet 2 Filed March 1, 1950 IN VEN TORS Emu/m0 /C //OHMANN By fl/va dol /NT DRA V/A/SAI M a/Mm ATTOR/Vfif Patented Sept. 8, 1953 UNITED STATES PATENT OFFICE LOCK STITCH SEWING MACHINE UNDER BED MECHANISM ration of New York Application March 1, 1950, Serial No. 147,092

12 Claims. (01. 112-203) The general object of the present invention is to provide improvements in the under-bed mechanism of a lock stitch sewing machine. The invention was primarily devised for use in the construction of a portable sewing machine of relatively small size.

A specific object of the invention is to provide a novel under-bed stitch forming and feed actuating unit which is detachably secured in the hollow base portion of the sewing machine frame, and which includes all of the under-bed sewin machine mechanism except the feed dog, and a portion of its operating mechanism. Another specific object of the invention is to provide a desirable form of feed mechanism in which the feed dog is given it different movements by means of cams or excentrics carried at the opposite ends of a shaft mounted in the body of the above mentioned unit.

Other specific objects of the invention are to provide improved means for releasably securing the bobbin casing, or holder, in the open ended rotary hook of the sewing machine; and to make the bobbin casing accessible for inspection, the removal of clogging thread accumulations, and bobbin replacement, and to facilitate such replacement; and to adapt the bobbin casing for use with ordinary thread, and also with thread or cord of much larger diameter than the ordinary thread.

The various features of novelty which characterize our invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages, and specific objects attained with its use, reference should be had to the accompanying drawings and descriptive matter in which we have illustrated and described a preferred embodiment of the invention.

Of the drawings:

Fig. 1 is an elevation of a sewing machine with parts broken away and in section;

Fig. 2 is an inverted plan view of the machine shown in Fig. 1;

Fig. 3 is a partial elevation in section on the lines 33 of Fig. 1 showing a portion of the feed mechanism;

Fig. 4 is a partial elevation in section on the line 4-4 of Fig. 1;

Fig. 5 is a plan view showing a portion of the apparatus shown in Fig. 9, including the bobbin holder and associated bobbin holder positioning element;

Fig. 6 is a partial elevation in section on the line 6-6 of Fig. 5;

Fig. 7 is a partial elevation in section on the line of Fig. 6;

Fig. 8 is a partial elevation in section on the line 8-8 of F g. 2 showing another portion of the feed mechanism; and.

Fig. 9 is a perspective view of a detachable, underbed, stitch forming and feed actuating unit.

In the drawings, we have illustrated an embodiment of the invention comprising a sewing machine frame, which may be an aluminum die casting, comprising a hollow structure includin a base A, standard B, arm C and needle bar head D. The base A is of box form open at its lower side, though, if desired, the opening may normally be closed by a detachable bottom wall part The integral top Wall portion a of the base A serves as the cloth plate or work bed of the machine. An electric drive motor F is mounted in the hollow base and rotates a drive pulley F, and through the latter is connected by a belt f to, and rotates a horizontal needle bar shaft G mounted in the arm C. A main underbed shaft H is rotated by the shaft G through a belt 9. The latter is of the sprocket chain type running over notched pulleys or sprocket wheels G' and H carried by the shafts G and H, respectively, and may well be of the particular form known as a Gilmer belt.

The shaft H forms part of an under-bed stitch forming and feed actuating unit shown in perspective in Fig. 9, and comprising a metallic body member I, which may be an aluminum die casting, and is normally in engagement with the work bed a and detachably secured to the latter by three screws l. The shaft H is journaled in front and rear bearing sleeves z and i anchored in the unit body I, and carries a gear 2 between said bearings. The gear 2 is in mesh with a gear 3 carried by a short hook shaft h parallel to and alongside the front end portion of the shaft H. As shown, the gears 2 and 3 are helical gears proportioned to drive the hook shaft h with a rotative speed twice that of the main under-bed shaft H. The shaft h is journaled in the member I and carries an open hook J of conventional form at its front end. The member I is formed with a lubricating chamber 5 having an opening at its bottom which is normally closed by a. removable cover plate 6. The chamber 5 is normally filled with lubricating oil or grease, and the latter not only lubricates the gears 2 and 3, but also provides lubrication for the adjacent bearings for the shafts H and h.

The unit includes a depending boss I at its front end, which, as is shown in Fig. 6, is formed with a passage 7 parallel to the shafts H and h, and receiving an arm or bar 8. The latter has its front end rigidly connected to a block like part 9 which forms an adjustable support for a bobbin casing positioning element K. The latter is connected by a pivot It to the support 9, to turn relative thereto about the horizontal axis of said pivot which is below and transverse to the axis of the hook shaft h. As shown, the arm 8 is in the form of a cylinder havin its under side flattened for engagement by set screw II threaded through the lower portion of the wall of the passage l. The screws ll not only maintain the flattened side of the arm 8 horizontal, but also secures the arm in the slightly different longitudinal adjustment positions desirable under diiferent conditions. The positioning element K comprises a plate like part [2 facing the hook J and having its adjacent side formed with a central depression IS. The top portion of the part l2 comprises an uprising tongue M extending upward above shoulder portions lb of the part 12. Vertical thread channels l6 at opposite sides of the tongue I4 open at their lower ends into the depression 13.

The part [2 is spring biased to turn into its inclined position shown in dotted lines in Fig. 6, but is normally maintained in its vertical position, shown in full lines in Fig. 6, by a notched latch member IT. The spring biasing means for the part 12 may be of any usual form. As indicated in the arrangement shown diagrammatically in Fig. 7, the pin I is rigidly connected to the element K and is connected to the part 9 by a helical torsion spring I2 which surrounds a right hand end portion of the pin l0 as seen in Fig. 7, and is surrounded by the wall of a cavity 5 coaxial with the pin l0 and extending into the support 9 from the right hand side of the latter as seen in Fig. '7. The inner end l2 of the spring [2' is secured to the pin it. The outer end I? of the spring comprises a portion external to the member 9 and looped to form a projection laterally displaced from the adjacent side of the cavity 9 and extending into an opening formed for the purpose in the member 9 The notched latch member I! is pivotally connected to a post [8 carried by the support 9 to turn relative thereto about an axis parallel to the arm 8, and is spring biased to turn into the position in which the opposing walls of its notch l9 straddle a pin 29 carried by the member K, when the latter is in its normal upright position. The latch member i! may be manually turned out of engagement with the pin l9 when desirable, as when a bobbin in thebobbin casing L is to be removed or replaced. When the latch member I! thus releases the pin 20, the element K is turned its bias spring into its position shown in dotted lines in Fig. 6, whereupon the bobbin casing L normally tips out of its vertical position into its position shown in dotted lines in Fig. 6. The bias spring of the latch member I! may be a helical torsion spring like the spring 12, and like the latter, may be mounted in a cavity formed in the member 9 and have one end connected to the shaft carrying the member I! and have its other end connected to the support 9.

The bobbin casing or holder L may be of con ventional form in most respects, having the usual cup shape with a cylinder wall 2| and base member 2Ia forming a bobbin chamber, receiving a thread bobbin mounted on and rotatable about a central hollow spindle portion 22 of the bobbin holder. At its front side, the upper portion of the bobbin holder is formed with transverse shoulders or lips 23, which form the side walls of a slot like space which loosely receives the tongue portion of the positioning element K, in normal operation. The bobbin casing L is formed with a thread passage 24 in its cyindrical wall portion 2! for the passage into the annular space between the wall 2| and the bobbin case rim 25 of sewing thread of the usual diameter. An are shaped thread tension spring 28 secured to the wall 2t, subjects the portion of the thread. passing through the opening 24 to suitable ten sion. A special feature of the bobbin holder is the formation in its wall 2| of a separate outlet passage 2? for a thread or embroidery cord which is substantially larger in diameter, and stiffer, than ordinary sewing thread, and which, because of its size and stiffness, requires no such tension action as is provided by the spring 25. Such large diameter thread or cord may be used in forming ornamental stitching on goods. The thread passes away from the annular channel between the wall 2! and the rim 25 to the needle path through an opening 28 in the portion of the bobbin casing rim 25 adjacent the lip 23 and between the latter and the thread passage 21.

The means disclosed for supporting the bobbin casing L and making it accessible for removal and replacement when one bobbin is to be placed by another, are relatively simple and effective. When the bobbin case support K is tilted into its inclined position shown by dotted lines in Fig. 6, the bobbin case may be readily grasped by the fingers of the operator inserted through an opening formed for the purpose in the bed plate a between the pressure foot and the end wall a of the base A, and normally closed by a removable plate 2%. The bobbin case may be returned to its position shown in dotted lines in Fig. 6 with equal ease. Thereafter the bobbin case L and its portioning device K may then be returned to their normal positions shown in full lines in Fig. 6 by light finger pressure applied to the upper end of the member K. The latch member I? is spring biased for counter clockwise rotation about the post i8 as seen in Fig. 4, and the support K is spring biased for clockwise movement about the pivot IQ, as seen in Fig. 6, and. in consequence the movement of the bobbin case L and support K out of their positions shown in full lines and into their positions shown in dotted lines in Fig. 6 is effected by merely turning the latch I! clockwise as seen in Fig. 4 to disengage the projection 20. When the bobbin casing and member K are returned to their normal condition, the bobbin casing is automatically latched in the rotary hook J by the spring biased latch member H. In the preferred form of the invention the plate 2e is in abutting relation with the usual throat plate 30, and extends between the latter and the front end of the top of the sewing machine base A.

An advantageous characteristic of the invention, is the ease and accuracy with which the bobbin casing supporting element 9 may be adjusted toward and away from the member I in the original assembly of the apparatus, and in subsequent reassemblies or adjustments which become necessary as a result of the replacement of the hook J, bobbin casing L or member K. To provide the proper clearance or thread space between the front side of the bobbin case and the adjacent surface of the member K, a clearance of about .012 to .015 of an inch is needed. The precise displacement of the member 9 from the body I required to provide such displacement may be effected by loosening the screws II, and then longitudinally adjusting the bar 8 in the boss I. This adjustment is easily effected when the member I is detached from the sewing machine frame, so that the adjustor is not hampered in effecting the adjustment, and can visually observe the relative positions of the bobbin casing and member K when the latter is latched in place by the member I1, and can readily insert a thin clearance gage between the bobbin casing and the member K.

An especial advantage of the bobbin case arrangement is the ease with which the bobbin casing L and its support K can be adjusted from their normal positions shown in full lines, into their positions shown in dotted lines in that figure, and the resultant reduction in the annoyance and trouble caused by the accumulation of thread in and adjacent to the bobbin casing which occurs as a result of thread clogging. Such thread clogging is especially apt to occur, and its results are especially annoying and troublesome, when the house-Wife or other user of a sewing machine is not mechanically minded or trained and has had little experience in operating sewing machines. With the bobbin case arrangements in most general use, thread clogging is especially troublesome because of its tendency to prevent the removal of the bobbin casing from the rotary hook of the sewing machine.

Ordinarily when clogging occurs and results in thread accumulation in and adjacent to the bobbin casing of the sewing machine disclosed herein, the movement of the latch member out of engagement with the pin 20 will result in the movement of the bobbin casing and member K into their tilted, dotted line positions shown in Fig. 6. Thereafter all that needs to be done to return the mechanism to its normal operating condition, is to lift out the bobbin casing, remove the accumulated thread, make certain that the thread is moving freely from the bobbin to and through the thread passage 28, return the bobbin casing to its position shown in dotted lines in Fig. 6, and tilt the member K and bobbin easing into their normal vertical positions.

The feed mechanism employed to move the work transversely to the path of the sewing machine needle over the cloth plate a, is characterized primarily by the simple means for supporting the feed dog 3| and giving it its feeding movement. In accordance with the present invention, the feed dog 3| is given its up and down movements by a cam or excentric 32 secured to the front end of the shaft H mounted in the body I, and is given its horizontal movements by a cam or excentric 33 secured to the rear end of the shaft H. Advantageously and as shown, each of the members 32 and 33 is a ring, i. e. a disc formed with an excentrically located round hole snugly receiving a corresponding end portion of the shaft H and secured to the latter by a set screw. The feed bar 34 to which the feed dog 3| is attached, is connected by a pivot pin 35 to the upper end of an arm 39. The latter has its lower end rigidly secured to an oscillating shaft 31. As shown, in Figs. 1 and 2, the shaft 31 is horizontal and has its ends pivotally supported by aligned trunnion pivots 31, which 6 are releasably secured in sockets in lug portions 38 of the frame base A, within and adjacent the ends of the latter. The shaft 31 is located at a level but little above the bottom of the base A, and is close to the vertical frame wall a at the operators side of the sewing machine. Adjacent its front end, the shaft 31 is provided with spaced apart uprising arms 39 which straddle the adjacent wide end portion of the feed bar 34 remote from the feed dog 3|. The feed bar 34 is formed at its underside with a bearing surface 40 adjacent its feed dog end, and is spring biased to maintain its bearing surface 40 in contact with the upper side of the excentric 32, so that the feed dog is moved up once, and down once, during different portions of each revolution of the shaft H. Normally, the up and down movements of the feed dog alternate with the to an fro horizontal movements of the feed dog.

The horizontal movements of the feed dog are produced by oscillatory movements of the shaft 3? which result from the rotation of the cam 33. The mechanism through which the rotation of the shaft H gives oscillatory movements to the shaft 31, is shown in Fig. 3. That mechanism comprises a lever 4| which extends transversely to the shaft H, and in a general horizontal direction, and is forked at one end having parallel upper and lower fork portions 42 and 43 which straddle the excentric 33, so that the corresponding end of the lever 4| is moved up and down during each rotation of the shaft H. The opposite end of the lever 4| is connected by a pivot 44 to an uprising arm 45 secured to the shaft 3! adjacent the rear end of the shaft H. Intermediate its ends, the lever 4| supports a roller element 46 pivoted to turn on its horizontal supporting shaft 47. The latter extends through and is anchored in the lever M and is nearer to the bifurcated end of the lever than to the pivot 44. The roller 46 is received in a guide-way between straight parallel walls 48. The guide-way thus formed is a slot open at its ends and open at its side adjacent the lever 4|, and is formed in a block like part 49 secured to the end of a shaft 50. The latter is parallel to the shaft H and is journaled in a boss 5| which depends from the under side of the top wall portion of the base A, adjacent the lower end of the frame standard B. A collar 52 is secured to the shaft 5;.) at the opposite side of the boss 5| from the guide-way part 49.

An uprising operating arm 53 has its lower end secured to the collar 52 and extends radially away from the latter upward through an elongated slot 54 in the portion of the top wall of the base A at the right of the standard B as seen in Fig. 1. The arm 53 forms a means for angularly adjusting the shaft 59 and thus varying the inclination to the horizontal of the side walls 43 of the guide-Way receiving the roller 45. When those side walls are vertical, the small up and down movement given to the forked end of the lever 4| produces no significant angular movement of the shaft 31. Under this condition in which the shaft 31 is not oscillated. the feed dog is given no horizontal to and fro movement, which is desirable under some conditions, as in using the machine to effect darning operations. When the upper end of the lever 53 is pulled toward the user, the upper ends of the walls 48 are shifted to the right of their respective lower ends as seen in Fig. 3 and the shaft 31 is then given oscillatory movements as required to cause the feed dog to advance the work in the normal direction, i. e. away from the user of the sewing machine.

When the user pushes the upper end of the arm 53 to the rear and thus adjusts the member 49 in the counter clockwise direction, as seen in Fig. 3, beyond the position in which the guide-way walls 38 are vertical, the normal direction of feed is reversed, and the feed mechanism then moves the work toward the user. Ordinari y when the direction of feed is being reversed, the sewing machine user needs to guide the work with one hand While adjusting the direction of feed with the other hand. The location of the leve 53 at the right hand, or rear end of machine. and its extension upwards from the base of the machine, facilitates the adjustment of the lever 53 by the users right hand while the work is being positioned by her left hand.

The feed mechanism disclosed is characterized by its simplicity and effectiveness. In most domestic sewing machines now in use, the horizontal feeding movements of the feed dog are effected as a result of oscillatory movements given to a shaft similar or analogous to the shaft 31 shown herein, through a long lever connected at its lower end to said shaft and extending upward through the standard portion B of the sewing ma chine frame and having its upper end operatively connected to the needle bar actuating shaft G. The use of applicants short lever d! has obvious practical advantages, and contributes directly to a reduction in the sewing machine construction and assembly costs. It also permits the length of the stitches formed to be regulated and the direction of the feed to reverse by the angular ad- ,iustment of the conveniently located, readily accessible and easily operated handle 53.

As shown, the sewing machine is provided with a thread spool supporting spindle 55, and take up mechanism 55, a tension device 51, a needle bar 58, and a needle 59 all of which may be conventional in form and arrangement and therefore require no further mention herein. In some cases, the relatively short work bed a may be extended, when desirable, by means of an extension plate as detachably connected by longitudinally adjuslh able pivot pins or hinge pintles 6|, to the frame base A at the front end of the latter. As shown in Fig. 1. the extension plate 50 is turned upward into a non-operative position in which its upper end bears against the needle head D. When the part 69 is turned down into its normal horizontal position, a flange portion 62 of the member 6!! bears against the front end wall a of the frame A.

The major advantages obtainable with the present invention are directly due to, or stem from our novel detachable under-bed, stitch forming and feed actuating unit, comprising the body or frame member I, the main under-bed shaft H, the hook shaft h, and the bobbin casing mechanism supported by the member I. Attention has already been directed to various advantages obtained by the adjustable mounting of the bobbin case adjusting mechanism on the member I, and to some of the advantages of the actuation of the feed dog 3| by the cams or excentrics 32 and 33 mounted on the opposite ends of the shaft H.

In addition to its other advantages, the use of the detachable unit comprising the frame member I contributes directly to a significant reduction in the cost of constructing and assembling the undenbed sewing machine mechanism, by

reducing the machining operations on the frame base A and on the parts mounted in the base A and for that reason made less accessible for machining purposes than when mounted in the detachable member I in accordance with the present invention. The use of the novel unit, including the detachable frame member I, not only reduces the sewing machine construction and assembly costs, but it also contributes to the production of a sewing machine of improved construction. Thus, for example, the rigid and obviously desirable attachment of the two feed dog actuating cams 32 and 33 to the opposite ends of the same shaft H is made practically feasible by the mounting of the shaft H in the member I. With the shaft H so mounted, simpler actuating connections between the feed shaft 31 and the means for giving the feed dog its movements, and the practical elimination of lost motion in the feed mechanism are made possible.

In consequence of the simple connections and practical elimination of 10st motion, no provisions need be made for adjustment of the cams 32 and 33 relative to one another to insure the proper relative positions of the cam which will properly time the up and down and to and fro movements of the feed dog. Without arrangement the only timing adjustments which need to be made in assembling the sewing machine, is the tightening up of the set screws which secure the sprocket type pulleys G and H to their res ective shafts G and 1-1, after the beak J of the rotary hook J and the needle bar 58 have been adjusted into their proper relative positions in s e convenient state of operation. As will be rent, general advantages of the detachable 1 it are obtainable with rotary hooks of other it than that disclosed herein.

While in accordance with the provisions of the statutes, we have illustrated and described the best form of embodiment of our invention now known to us, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of our invention as set forth in the appended claims and that in some cases certain features of our invention may be used to advantage without a corresponding use of other features.

Having now described our invention, what we claim as new and. desire to secure by Letters Patent, is:

1. In a lock stitch sewing machine, comprising a frame including a Work-bed and a needle actuating mechanism above said bed, the improvement comprising an under-bed stitch forming and feed actuating unit for detachable connection to the under side of said work-bed and comprising a body member, a rotary hook and a hook driving shaft journaled in said member, a cam carried by said shaft at one end and operative to give a feed dog horizontal to and fro movements, a second cam carried by said shaft at its other end for giving said feed dog up and down movements, and bobbin case supporting means, mounted on said member and maintaining a bobbin case in operative relation with said rotary hook.

2. A unit as specified in claim 1 in which said hook is carried by a hook shaft which is gear connected to said hook driving shaft.

3. A unit as specified in claim 1 in which said hook driving shaft extends through said body member and has end portions extending away from the respective ends of said body member and in which one of said cams is mounted on one of said end portions and the other cam is mounted on the other end of said portions so that each cam is adapted to engage a feed mechanism part in overlapping relation with an end portion of said body member.

4. A unit as specified in claim 1 in which said rotary hook is mounted in said body member to rotate about a horizontal axis and in which said bobbin case supporting means comprises a part detachably connected to said body member and adjustable relative thereto in a direction parallel to said axis.

5. A look stitch sewing machine comprising a frame including hollow base, standard and arm, and a needle bar shaft journaled in said arm and carrying a pulley directly above said standard, an under-bed, stitch forming and feed actuating unit comprising a body member detachably secured to said frame base, a hook rotating shaft journaled in said body member with one end portion extending therefrom into the space directly beneath said standard, a pulley secured to said end portion adjacent said body member, a cam secured to said end portion at a greater distance from said body member, a timing belt connecting said pulleys, a feed bar oscillating shaft journaled in said base and parallel to said hook actuating shaft and having a transverse arm, a lever having one end connected to said arm to turn about an axis parallel to said shaft and having fork portions at its opposite end which straddle said cam, and having a lateral projection adjacent its forked end and a guide member mounted in said shaft and formed with a guide way open at one side and extending transversely to said axis and receiving said lateral projection whereby the rotation of said cam through a particular portion of each revolution oscillates said feed shaft in one direction or in the opposite direction, depending on the angular adjustment of said guide member.

6. A lock stitch sewing machine as specified in claim 5, in which said needle bar shaft carries a second pulley, and comprising a motor mounted in said base and having a driving pulley, and a driving belt running over the two last mentioned pulleys.

7. A lock stitch sewing machine as specified in claim 5 in which said hook actuating shaft supports a second cam at its end remote from the first mentioned cam, and in which said oscillating shaft has a second uprising arm, and comprising a feed bar pivoted at one end to said uprising arm to turn about an axis parallel to said oscillating shaft and having a bearing surface at its under side resting on said second cam.

8. A sewing machine comprising a frame having a hollow base portion and an uprising standard with depending side and end walls, a hook actuating shaft journaled in said base portion to turn about an axis intersecting said end walls and intermediate said side walls, a separate cam carried by said shaft adjacent each end, an oscillating feed shaft journalled in said hollow base to turn about an axis parallel to the first shaft and adjacent the lower edge of one of said side walls and having an uprising arm at each end, a feed bar pivotally connected to the uprising arm remote from said standard to turn about an axis parallel to said oscillating shaft and having a bearing surface intermediate its ends resting on the cam carried by the adjacent end of said hook actuating shaft, a lever pivotally connected to the upper end of the arm adjacent said standard to turn about an axis parallel to said oscillating shaft, the opposite end of the lever having spaced apart fork portions straddling the second cam carried by the actuating shaft, said lever having a lateral projection at one side adjacent its said opposite end, a guide member mounted to turn about an axis parallel to said oscillating shaft and formed with a guideway open at one side to receive said projection, and having parallel guide walls at opposite sides of said projection adapted to be turned by the rotation of said member from a position in which said guide walls are inclined away from the vertical in one direction into a position in which they are inclined away from the vertical in the opposite direction, whereby the feed mechanism is adjusted to feed work in one direction or in the opposite direction, said base portion being formed with a slot in its top wall adjacent said standard, and an arm extending through said slot and having its lower end attached to said guide member and operative to oscillate said member about its axis.

9. Bobbin case supporting means operative to normally maintain a bobbin case in an open ended rotary sewing machine hook turning about a horizontal axis and adjustable to effect the removal and replacement of the bobbin case and comprising a bobbin case supporting member mounted to turn about a horizontal pivot below and transverse to the axis of said hook and biased to turn from a normal upright position in which it is adapted to hold a bobbin case in said hook, into an inclined position in which the bobbin is withdrawn from the hook and is accessible for removal and replacement, supporting means including a shaft parallel to and substantially below said hook axis, an uprising latching member pivoted on said shaft and biased for movement about the latter into a position in which it engages a portion of said supporting member at a level adjacent that of said hook axis and latches said supporting member in its upright position.

10. A sewing machine bobbin case adapted for use in sewing either with a first thread of one diameter or with a second thread of greater diameter and stiffer than said first thread, and comprising a cup shaped casing having a base member and cylindrical wall extending therefrom and forming a bobbin chamber, and a circumferential rim extending away from said wall, said wall being formed with a first thread outlet and with a second thread outlet angularly displaced from said first thread outlet, each of said outlets being formed as an inclined slot extending from an edge of the said wall, the casing having a needle opening therein and said rim being formed with a transverse opening at a greater distance from said first thread outlet than from said second thread outlet for the passage of thread received from said second thread outlet, and a spring attached to said bobbin casing and operative to tension the thread passing through said first thread outlet.

11. A bobbin case as specified in claim 10, in which said rim opening is adapted to receive thread from each of said thread outlets.

12. An under-bed stitch forming and feed actuating unit for lock stitch sewing machines having a frame and including a work-bed and a needle actuating mechanism mounted in said frame above said work-bed, said unit comprising a body member for detachable connection to the underside of said work-bed, a rotary hook and a hook driving shaft journaled in said member, a

11 cam carried by said shaft at one end and operated to give a. feed. dog horizontal to and fro movements, and a second cam carried by said shaft at its other end for giving said feed dog up and down movements.

RICHARD K. HOHMANN. JOHN T. DRAVINSKI.

Name Date Free Feb. 25, 1902 Number Number Name Date Mack Feb. 18, 1913 Gould Feb. 10, 1914 Ruckstuhl May 9, 1916 Eames Dec. 17, 1935 Chason Oct. 20, 1942 Best Nov. 4, 1947 

